Seasons have changed! Fall officially began on Saturday at 2:50 a.m. We have been losing daylight rapidly over the last few weeks. Each day around the start of fall, we lose about 2 minutes and 45 seconds of daylight. The sun came up at 7:16 a.m. in Cleveland on Saturday and will set around 7:23 p.m.
That gives us 12 hours and 7 minutes of daylight. But wait a minute...shouldn't the sunrise and sunset be exactly 12 hours apart on the Equinox with 12 hours of daylight and nighttime?
One of the reasons this happens is because of latitudes. Interestingly, the date when there are "nearly" equal parts day and night happens a few days after the autumnal equinox. The specific dates for this occurrence are different for different latitudes. For our latitude, this will happen on September 26 with 11 hours and 59 minutes of daylight. For observers within a couple of degrees of the equator, the period from sunrise to sunset is always several minutes longer than the night. At higher latitudes in the Northern Hemisphere, Daytime continues to be longer than nighttime until after the September equinox.
On the day of the equinox, the geometric center of the Sun's disk crosses the equator, and this point is above the horizon for 12 hours everywhere on the Earth. However, the Sun is not simply a geometric point. Sunrise is defined as the instant when the leading edge of the Sun's disk becomes visible on the horizon, whereas sunset is the instant when the trailing edge of the disk disappears below the horizon. At these times, the center of the disk is already below the horizon.
Additionally, atmospheric refraction (or bending) of the Sun's rays causes the Sun's disk to appear higher in the sky than it would if the Earth had no atmosphere. Thus, in the morning, the upper edge of the disk is visible for several minutes before the geometric edge of the disk reaches the horizon. Similarly, at sunset, you can see the sun for a few minutes after it has dipped below the horizon. This also means that every day is longer due to refraction and not just on the equinox!
Want the latest Power of 5 weather team updates wherever you go? Download the News 5 App free now: Apple|Android
Download the StormShield app for weather alerts on your iOS and Android device: Apple|Android
Click here to view our interactive radar.
Read and watch the latest Power of 5 forecast here.
Follow the News 5 Weather Team:
Mark Johnson: Facebook & Twitter
Trent Magill: Facebook & Twitter
